If I create some userscripts for Tampermonkey (or similar applications) I will put them here.
Userscript that replaces the favicon on MyAnimeList with the old one. On Firefox it only changes the icon on the tab itself; on Chromium it also changes the icon in the bookmarks. Replace the websites/icon source to use it in other places.
// ==UserScript==
// @name MAL Icon Changer
// @namespace https://and-all-your-trash.neocities.org/
// @version 1.0
// @description Changes the icon on MAL to the old one.
// @author https://and-all-your-trash.neocities.org/
// @match *://myanimelist.net/*
// @icon https://and-all-your-trash.neocities.org/img/btn/faviconv5.ico
// ==/UserScript==
(function() {
'use strict';
var link = document.querySelector("link[rel~='icon']");
link.href = 'https://and-all-your-trash.neocities.org/img/btn/faviconv5.ico';
})();